This paper argues that before the world started to globalize, the differences in the geographical endowments that different population faced were the most important constraints to their long-term production and consumption. The paper uses this central hypothesis to explain the sharp contrast between the flourishing Song and the stagnant Ming and Qing. During the Song dynasty, despite the fact that China lost a significant amount of arable land to invading nomads as its population peaked, China witnessed a higher urbanization level, more prosperous commerce and international trade, and an explosion of technical inventions and institutional innovations. However, after having significantly improved its man-to-land ratio in the period after the Song China only found itself induced deeper into the agrarian trap, resulting in reduced urbanization, withering foreign trade, a declining division of labor, and stagnant in technology.